Calculus 8th Edition

$\bf True$.
$\bf True$. Because $y(x)^{4}\geq 0$ for all $x$, so that $-1-y^{4}$ is strictly negative for all values of $x$. Hence, if $y$ satisfies $y-=-1-y^{4}$, this means that $y'$ is strictly negative for all $x$ . By the first derivative test , this means that $y$ is decreasing.